A New Class of Molecular-Based Photoelectrochemical Cell for Solar Hydrogen Production Consisting of Two Mesoporous TiO₂ Electrodes

A new class of molecular-based photoelectrochemical cell for solar hydrogen production consisting of a TiO2-based photoanode modified with a polypyridyl ruthenium photosensitizer (Ru-qpy) and a TiO2-based cathode modified with a platinum porphyrin H2 evolution catalyst has been investigated, showing that the electron accumulation at the conduction band of TiO2 at the photoanode is promoted via electron injection from the Ru-qpy together with hole scavenging by a sacrificial donor. Our study here for the first time unveils that the upward shift given in the Fermi level of the TiO2 at the photoanode provides an electromotive force required to flow electrical current leading to solar hydrogen production from water even without applying external electrical bias.